Abundância e diversidade da fauna de camarão e peixe na floresta de mangal da ilha de inhaca: um estudo comparativo entre o saco e a baía de sangala

Abstract

A comparative study of the abundance and diversity of shrimp and fish fauna was carried out in the Saco and Baía Sangala mangroves, in Inhaca Island, in the months of March and April 2001 in two consecutive tides. In each study area, three sub-areas were chosen taking into account their position in relation to the flood, where samples were taken using fixed nets, during spring tides. Additional samples were taken from adjacent channels through two funnel-shaped nets and a lm and 0.6m diameter net opening. The results obtained indicate that temperature, salinity and depth did not show great variations between the two areas and between the sub-areas. A total of 2045 fish specimens were obtained, corresponding to 25 species, of which 815 specimens and 21 species were collected in Saco and 1230 specimens belonging to 16 species were collected in Sangala Bay. A total of 87 fish specimens were obtained in the channels, corresponding to 7 species, of which 85 specimens and 7 species collected in the Saco channel and 2 specimens of 2 species in the Sangala Bay channel, with the same species occurring in Sangala of the Bag of Inhaca. In total, 6.33 kg of fish were also collected, with an average biomass of 0.0037 kg/m2 in Saco and 0.0098 kg/m2 in Sangala Bay. were higher in Saco (0.29 and 0.095) compared to Sangala Bay (0.20 and 0.08) the Saco channel had the highest diversity and evenness indexes (0.37 and 0.12) in relation to to the Sangala channel (0.01 and 0.04). A total of 659 shrimp specimens were obtained, of which 28 belonged to other non-penaeid groups. 95.4% of the penaeids were collected in Saco and 4.6% in Sangala Bay. In both areas the species Penaeus indicus had the highest percentages 87% and 41% in Saco and Baía de Sangala respectively. The highest percentages of capture in the two study areas were made in the external sub-area. The results obtained indicate that both the Saco da Inhaca and the Sangala Bay are important habitats for economically important fish and shrimp juveniles, therefore, there is a need for their conservation, thus ensuring the sustainable use of fisheries resources. (TRADUÇÃO NOSSA)